Maybe they can just add it for the overworld portals but not for netherportals like with entities

Maybe when water flows down in the Nether it turns into Hot Water (only in the Nether Of Course)

That'd be interesting, would fix the visual oddity of water cutting off halfway below alternate2 generation

water logged portal block when

I would actually love this, I wonder how they would do it though with water in the nether though. I think it would be cool to see something more than just a harsh stop of all the water, but I don't know what else they could do about it.